Film cooling instability analyses for trailing edge cutback with a novel linear sand-dune inspired lip under mainstream pulsation

Inspired by natural linear sand-dune (LSD), the present work proposed a cutback cooling configuration with novel lip design applied in trailing edges of gas turbine blade. By time-resolved experiments and large eddy simulations, transient flow and film coverage performances of the novel configuration are investigated, and the effect of inevitable mainstream pulsation is included. Through the analyses of unsteady flow characteristics, the LSD lip design can help hinder the propagation of mainstream pulsation, and generates a series of separation wakes to destroy the highly-unsteady shedding vortices, which leads to a high film effectiveness and low level of cooling instability. Quantitatively, by the novel design, time-averaged film effectiveness can be locally increased at least 26% and the unsteadiness level can be maximally reduced by 86% compared to the baseline elliptic lip design. The analyses on probability distribution of transient film effectiveness also conform an obvious advantage of LSD design, from the perspective of statistics. Additional aerodynamic loss induced by the LSD lip is always less than 7% in both steady and pulsed conditions, which remains low and is worthy considering the significant improvement in cooling performance.